Japanese Patent Publication No. 2000-318565 describes an airbag apparatus designed for fast deployment to protect the head of the vehicle occupant. This airbag apparatus incorporates a tube-shaped 1st gas channel formed along the edge of the airbag corresponding to the occupant's head, a 2nd gas channel formed along the boundary area of the airbag corresponding to occupant's head and shoulder and having one end connected to the 1st gas channel, a gas inlet port connected to the 1st gas channel as means of directing gas from the inflator. An upper gas exhaust port connected to the airbag corresponding to the occupant's head and a lower gas exhaust port connected to the airbag corresponding to the occupant's shoulder are formed in the 2nd gas channel.
U.S. Pat. No. 6,270,113 describes a side airbag apparatus which is designed to completely deploy along the vertical plane before deploying completely in the forward direction. The airbag structure includes a 1st side panel, a 2nd side panel, a cylindrical panel, and a partition panel. The undeployed airbag is stored in a compressed state, and when deployed, enters the space between the occupant and the side of the vehicle. The outer portion of the airbag is formed by the joining of the 1st and 2nd side panels, the rear portion of the airbag is formed by the joining of the rear edges of the 1st and 2nd side panels, and the bottom of the airbag is formed by the joining of the bottom edges of the 1st and 2nd side panels. A part of the bottom portion of the airbag is open to receive inflation gas from an attached inflator, and both sides of the cylindrical panel are fixedly attached to corresponding positions of the 1st and 2nd side panels in order to form a cylindrical part extending upward along the rear edge of the airbag. The partition panel is attached to the 1st and 2nd side panels and the cylindrical panel so as to define and separate upper and lower airbag chambers disposed in front of the cylindrical part.
The above-noted side airbag structures, particular the type designed to restrain the occupant's hip region on the seat cushion, exhibit the following shortcomings when installed to a seat having a mechanical device located at the lower part of the backrest.
A fold flat seat, that is, the type of seat in which the backrest part folds down to a horizontal position over the seat cushion part, requires that the fold-flat hinge is attached at a point above the joint of the reclining mechanism on the side of the backrest. The inflator of the side airbag apparatus and the side airbag itself are attached to the side of the backrest. As a result, the side airbag and inflator must be installed to the backrest at a point well above the seat cushion and the fold-flat hinge. Because this installation requires that there is a long distance between the airbag attachment point and the seat cushion part to be restrained by the airbag, a problem arises in that it takes a relatively long period of time for the deployed side airbag to reach the part of the seat near the occupant's hips.
The inflation gas must flow predominantly in the downward direction in order for the side airbag to reach the hip region quickly, but because the fold-flat hinge is positioned directly beneath the side airbag and inflator, it becomes necessary to structure the side airbag in a way which avoids the area around the fold-flat hinge. Structuring a side airbag apparatus in this manner, however, raises another problem that the inflation gas flows in a forward direction (toward the front of the vehicle) along the configuration of the side airbag, rather than in the desired downward direction. Thus, a greater amount of time is required for the airbag to reach the seat occupant's hip region.
Accordingly, there is a need for a side airbag system which addresses these shortcomings. In consideration of the above noted shortcoming, the side airbag apparatus for a vehicle invention has been designed for installation to a vehicle seat having a fold flat hinge mechanism of the type which allows the backrest to fold down flat over the seat cushion. The purpose of the side airbag apparatus invention is to deploy the side airbag quickly to the region adjacent to the seat cushion in vehicular applications where an airbag is intended to provide adequate occupant restraint at the seat cushion.